Generally speaking, the mainpiece of a rudder is supported by the boat by means of at least two bearings, that is either smooth bearings or ball bearings or needle bearings or even cylindrical roller bearings allowing the rudder blade to rotate.
Owing to the particular hydrodynamic forces possibly exerted transversally on the rudder blade, especially in difficult sea conditions, the mainpiece of the rudder may be subjected to bending deformations inducing an embedding force in these bearings which, when combined with a shearing force, strongly stresses the structure of the boat. These forces thus provoke a premature fatigue of the rudder mainpiece and the boat structure close to the bearings. Similarly, the induced deformations provoke premature wear of the mainpiece guides, this frequently requiring that the latter be replaced.
One conventional solution aiming to overcome these drawbacks consists of providing extremely solid, heavy and expensive mainpieces, mainpiece supports and a boat structure so as to avoid any ill-timed ruptures during navigation. Consequently, it is preferable to avoid implementing these solutions by using spherical rocker bearings or spherical ball bearings or barrel-shaped roller bearings. However, the drawback of these materials is the fact that they are extremely expensive, require constant maintenance to ensure correct functioning and are moreover extremely fragile, having regard to a marine environment.
Furthermore, the time involved in changing bearings in the event of the latter becoming worn or broken proves to be long and arduous as these elements need to be forcefully mounted, indeed often permanently cemented.